In the manufacture of multi-part business forms, it is customary to print the various sheets of the form on separate continuous rolls of paper.
The continuous rolls or webs of paper bearing the different parts of the form are then run through a collating and gluing machine in which the various parts of the form are overlaid one with the other, and are interleaved with sheets of carbon paper. An edge or two edges of the form are glued in such a machine, and the completed multi-part form sets are then cut off and stacked.
It is highly desirable that the number of form sets in the stacks should be as near as possible exact. In the past the counting of forms has been somewhat inaccurate. In addition, it has involved the use of an extra employee on the stacking unit with consequent increase in operating cost. In addition, it has generally speaking not proved to be practical to run such stacking units above a predetermined relatively low speed. This in turn has limited the speed at which the collating and gluing units could be run. All of this therefore greatly increases the cost of manufacturing multi-part business forms.
Various problems arise in connection with automatic counting and stacking of multi-part business forms at a high speed. For example, different multi-part form sets may be of different thicknesses. The various sheets of the forms are relatively thin and flimsy and are liable to become unglued or dislodged, and require to be handled with great care. Excessive pressure during counting and stacking of such form sets may result in carbon impressions being produced on the lower copies of the forms which will detract from their appearance.
The faster such machines are run, the more difficult it is for an operator to control the counting and stacking of individual bundles of such forms.
The automatic stacking of such multi-part forms also involves a requirement for jogging the stacks of forms so that they are square. This in turn presents something of a problem since each multi-part form set is itself a bundle of as many as five sheets of paper and four sheets of carbon and is therefore relatively bulky. In addition the size and bulk of each of such multi-part forms creates a further problem in that as the speed of operation of such a stacking machine is increased, the velocity of the form set is greatly increased. Any impact between such a form moving at high speed and a stationary part of the machine will therefore produce a tendency for the form to buckle or be deflected causing further problems.
When starting up the collating and gluing machine it is inevitable that the first few collated and glued forms will be faulty for some reason. It is desirable that they should be rejected and not passed through for stacking.
In the past the rejection of faulty forms has usually been carried about by visual inspection and manual selection. Again, this is unsatisfactory for high speed operation.
In order to run a stacking machine at high speed, it has been found that it is generally speaking preferable to operate with two alternate stacking stations. One stack of a predetermined number will be completed at one station after which the supply of forms will be diverted to the other stacking station and so on to and fro.
The diverting of the forms from one station to the other also presents a problem since if a precise count of forms in each stack is to be achieved, then the diversion must take place in timed relationship to the stacking of the forms.